Water- and corrosion-resistant lubricating greases gelled with inorganic colloids



WATER- AND CORROSION-RESISTANT LUBRI- CATING GREASES GELLED WITH INORGANIC COLLOIDS Ronald Sowerby Teale, Beaconsfield, England, and Hans Seeles, Hamburg, and Helmut Richard Karl Ferdinand Rolf Konau, Hambisrg-Ghlsdorf, Germany, assignors to Shell Development Company, New York, N. Y., a corporation of Delaware No Drawing. Application February 29, 1956 Serial No. 568,431

Claims priority, application Great Britain May 2,1955

7 Claims. (Cl. 25228) This invention relates to improved grease compositions. More particularly, it is concerned with greases gelled with inorganic colloids and improved with respect to water resistance and corrosion protection by the presence of certain haloepoxides.

Lubricating greases contain a lubricating oil base and a gelling agent. The gelling agent is usually a soap of a fatty acid or a hydroxy fatty acid. Soaps are subject to phase changes as the temperature increases, so that soap-gelled lubricating greases soften at elevated temperature and finally become liquid.

Inorganic colloids have already been used as gelling agents in lubricating greases. Lubricating greases containing such gelling agents are able to retain their consistency over a far Wider temperature range.

Lubricating greases containing an inorganic gelling agent generaly have, however, a poor resistance to disintegration by the action of water. In order to improve such lubricating greases in this respect surface-active agents, such as long chain amines, amides, ammonium salts and salts of higher fatty acids, have already been incorporated therein.

It has now been found that aliphatic compounds containing a halogen atom and an epoxy-oxygen atom (e. g. haloepoxyalkanes), are effective to improve the water resistance of lubricating greases containing an inorganic gelling agent. The said aliphatic compounds have the additional advantage of improving the corrosion properties of lubricating greases at the same time; this is particularly the case when the greases are applied to highly sensitive steel surfaces.

The expression epoxy-oxygen atom means an oxygen atom which is present in a radical of the following formula:

Accordingly, the present invention provides a lubricating grease comprising a hydrocarbon lubricating oil base, thickened to a lubricating grease consistency by means of a normally hydrophilic inorganic gelling agent, and a minor proportion of an aliphatic compound containing a halogen atom and an epoxy-oxygen atom. The preferred class comprises those compounds containing 3-10 carbon atoms per molecule, of which the chloroepoxyalkanes have the most satisfactory effect.

Patented May 27, 1958 ice Examples of suitable halo-epoxy aliphatic compounds are:

1,2-epoxy-3-chloropropane (epichlorohydrin) 2,3-epoxy-4-chlorobutane l,2-epoxy-3-isopropy1-3-iodopropane 1,2-epoxy-4-chlorobutane 1,2-epoxy-5-chloropentane 1,2-epoxy-3-methyl-3-chloropropan 1,Z-epoxy-S,3-dimethyl-3-chloropropane 1,2-epoxy-2-methyl-3-bromopropane 2,3-epoxy-4-methyl-l-chlorohexane 1,2-epoxy-4-methyl-5-bromopentane These compounds are added to the lubricating greases in minor proportions. The proportion used depends, among other things, on the desired improvement of water resistance and the amount of hydrophilic inorganic gelling agent present in the grease. Generally the proportion of the aliphatic compound lies between 0.01 and 3% by weight, based on the whole lubricating grease. In many cases a proportion of from 0.05 to 0.5% by weight (0.25%25% by weight of the gelling agent), and particularly of approximately 0.1% by weight, imparts satisfactory properties to the lubricating greases.

Although the said compounds improve the corrosion properties of the lubricating greases, a further improvement of these properties is generally obtained by adding a further anti-corrosion agent. The preferred anti-corrosion agents for this purpose are the aliphatic polycarboxylic acids containing one or more alkyl or alkenyl groups with at least 3 carbon atoms, and the corresponding thio acids, as well as the amides, anhydrides and esters of these acids. Examples of suitable acids are the malonic, succinic, glutaric, adipic, pimelic, sebacic, azelaic, tartaric, citric, maleic and citraconic acids which are substituted by alkyl or alkenyl groups of the type mentioned above, particularly those containing 10 to 18 carbon atoms. Examples of suitable amides and esters are the mono-amides of alkyl-substituted succinic acids, the mono-oleyl esters of alkenyl-substituted succinic acids and the mono-octyl esters of alkyl-substituted sebacic acids. Dimerized unsaturated fatty acids also are suitable corrosion inhibitors for use in these compositions.

When additional anti-corrosion additives are used these are employed in minor proportions, suitably in proportions of from 0.01 to 3% by weight, and particularly from 0.05 to 1% by weight, based on the whole lubricating grease.

A mineral lubricating oil is generally used as the hydrocarbon lubricating oil base. The mineral lubricating oils used may be of any origin and their properties may vary within wide limits. The viscosity generally lies within a range of 1 to 50 E. at 50 C. and the viscosity index between 0 and 80, but oils with a viscosity and a viscosity index outside these limits may also be used. While hydrocarbon oils are preferred as the grease base, other non-ester oleaginous fluids such as silicones and halocarbons (e. g. dimethyl silicone or hexachlorobutadiene) may be utilized.

Suitable gelling agents are the known normally hydrophilic inorganic gelling agents. Colloidal inorganic oxides, hydroxides, sulfides, sulfates, silicates and carbonates, such a silica, alumina, magnesia, calcium oxide, copper sulfide, calcium sulfate and mixtures thereof, particularly mixtures of silica withmagnesia, as well as Synthetic zeolites, and natural clays, such as hectorite and bentonite, may be used. The gelling agent is used in a proportion sufficient to thicken the lubricating oil base to the desired lubricating grease consistency. The proportion of the gelling agent generally lies between 2 and 20% by weight based on the whole lubricating grease.

If desired, minor proportions, e. g. 0.01 to 5% by weight, based on the whole lubricating grease, of other additives may be incorporated in the lubricating greases in orderto improve specific properties. As such may be mentioned, for example, anti-oxidants, especially phenolic anti-oxidants, suchas alkyl phenols, e. g. 2,6-di-tert.- butyl-4'-methyl"phenol, and amines,. such as phenylanaphthylamine, extremepressurc agents such as sulfur, lead naphthenate and sulfurized and/or chlorinated fats or fatty oils and tackiness agents such as rubber and 'poly-isobutylene, f 1

The lubricating grease's'may. be prepared by any one of theknown methods. For "instance, a volatile silicon compound, such as silicon tetrachloride, may be burnt in 7 meters long and 15 millimeters wide. The glass strip'is grease should extend above the water so that the degree of change of the grease may be better assessed. The strip is allowed to stand in the water for 48 hours at 20? C.

After this period it is determined how far the water has 7 become turbid and the grease has emulsified or decomthe vapor phase,[thus' forming a' colloidal silica which a may be dispersed in the lubricating oil base in any'desired way, e. g. by milling. It is also possible to start from a hydrogel and expel' the'water therefrom by means of a low-boiling organic liquid, such as methyl orethyl alcohol oracetone, after which'th e gel is heated to above the critical temperature of the liquid and the latter is evaporated. The resultant so-called aeorgel'is then dispersed in the lubricating oil base. the water present in a hydrogel by a waterand oilmiscible liquid, and then again expel the liquid by means of the lubricating oil base. In most cases, more than one organic'liquid is used.- The water'is first expelled,

' for example, bymeansof alcohol or acetone, this liquid It is also possible to expel,

being expelled by means of the lubricating oil base. The

additives desired in the lubricating grease can be incorporated in thejlubricating grease mixture at any stageof these processes, provided'of course, that such a stage is not chosen that the additives are Washed away or destroyed during the further course of the process. The following example illustrates the benefits of this invention; 0 I I 1 Three lubricating greases were prepared-having the The mineral oil was a lubricating oil with a viscosity of 19 Engler at C. obtained by distillation and extraction of a Venezuelan crude .oil.

The silicawas a colloidal silica obtained by'burning'in air hydrogen saturated with silicon tetrachloride. 1

In order to prepare the lubricating greases, the'oil was gradually poured'o n to thesilica, while constantly stirring.

ln preparingthe lubricating greases: B and. C, the epichlorohydrinand the anti corrosion agent were previously dissolved in the oil. The mLxture thus obtained was twice passed through a roll mill. Q 7 T I The penetration, water resistance and corrosion properties of the lubricating greases were determined.

The penetration was determined according to the A. S. .T. M. Method D217-48 (so-called .worked penetrationi), I j

The water resistance of the lubricating greases was tested in the so-ca'lled glass strip test? In this test a layerof grease lOO millimeters long, 10 millimeters wide and 1 millimeter thick is laid on a glass strip 160"milliposed.

In order to test the corrosion properties. the lubricating greases were applied in a thin layer on steel plates. A quantity of 2 grams of the grease to be tested was placed on the plates and then uniformly distributed over the whole plate by rubbing in at moderate pressure with a pad (twisted rag) which had, been previously soaked in the same grease. The plates were then placed in a glass cupboard for four weeks at 40 C., in an atmosphere with a relative humidity of in such a way as to be protected from water condensing on the glass wallsand running or trickling down. After this period the corrosion of the plates is assessed.

table:

' Resistance Lubricating grease Penetration to Water Corrosion of the plates 205 poor B weak to medium weak. 207 good very weak. 210 good traces.

a The grease decomposed completely.

tendency to emulsify; the water was still clear.

The unexpected improvementin Water resistanceoflthe compositions, caused by the additionof such. small quantities' of low 'molecular'weight materialste. g. epichloro llydrin) indicates the possibility that reaction may have occurred between the additive and the gel surface, or that the gel may have catalyzed the polymerization. of the additive to form poly(alkylene oxide) coatings having hydrophobic haloalkyl (chloromethyl) substituents. The remaining possibility'comprises simple. adsorption 10f the additive on the gel surfaces. We claim as our invention: 7 r

1. A grease composition consisting essentially iof a hydrocarbon lubricating oil, a grease-forming proportion of an inorganic hydrophilic colloidal gelling agent of the group consisting of inorganic oxides, hydroxides, sulfides,

sulfates, silicates and carbonates, and from about 0.01% to about.3% by weight of an aliphaticcompound having 7 3-10 carbon atoms per molecule and containinga halogen atom and an epoxy-oxygen atom, the amount of said compound being suflicient to improve the water resistant characteristicflof the grease. 1 i

2. A grease composition consisting essentially, of a mineral lubricating oil, a grease-forming proportion of an inorganic hydrophilic colloidal amorphous silica; gelling agent, and from about 0.01% to about 3% by weight of a monohaloepoxyalkane having '3 10 carbon atoms per molecule, the amount of'said alkane being 'suflicient 'to improve the water resistant characteristic of the grease.

3. A grease composition consisting essentially of a mineral lubricating oil, a grease forming proportion of an inorganic hydrophilic colloidal clay gelling agent and I from about 0.05% to about 1% by weight of a monochloroepoxyalkane having 3-10 carbonatoms per molecule, the amountof said alkane being sufiicientto improve the water resistant characteristic of the grease.

4. A grcasecomposition consisting essentially of a;

the amount of said alkane being sutficient to improve the water resistant characteristic of the grease.

The results of the tests are summarized in the following 5. A grease composition consisting essentially of a mineral lubricating oil, a grease-forming proportion of an inorganic hydrophilic colloidal silica gelling agent and from about 0.05% to about 1% by Weight of a monochloroepoxyalkane having 310 carbon atoms per molecule, the amount of said alkane being suflicient to improve the Water resistant characteristic of the grease.

6. A grease composition consisting essentially of a mineral lubricating oil, a grease-forming proportion of an inorganic hydrophih'c colloidal silica gel and from about 0.05% to about 1% by weight of epichlorohydrin.

7. A grease composition consisting essentially of a major proportion of a mineral lubricating oil and a grease- 6 forming proportion of an inorganic hydrophilic colloidal gelling agent of the group consisting of inorganic oxides, hydroxides, sulfides, sulfates, silicates and carbonates, rendered water-resistant by the addition of 0.01-3% by weight of a haloepoxyalkane having 3-10 carbon atoms per molecule.

Weike et a1. Mar. 20, 1956 Peterson et a1. May 29, 1956 

1. A GREASE COMPOSITION CONSISTING ESSENTIALLY OF A HYDROCARBON LUBRICATING OIL, A GREASE-FORMING PROPORTION OF AN INORGANIC HYDROPHILIC COLLODIAL GELLING AGENT OF THE GROUP CONSISTING OF INORGANIC OXIDES, HYDROXIDES, SULFIDES, SULFATES, SILICATES AND CARBONATES, AND FROM ABOUT 0.01% TO ABOUT 3% BY WEIGHT OF AN ALIPHATIC COMPOUND HAVING 3-10 CARBON ATOMS PER MOLECULE AND CONTAINING A HALOGEN ATOM AND EPOXY-OXYGEN ATOM, THE AMOUNT OF SAID COMPOUND BEING SUFFICIENT TO IMPROVE THE WATER RESISTANT CHARACTERISTIC OF THE GREASE. 